87-15: The Growth and Control of Nitrifying Bacteria in a Urea Plant CoolingA urea plant cooling water system experienced problems with the growth of nitrifying bacteria which produced nitric acid from ammonia resulting in a sharp drop in the pH of the cooling water was found to drop from 7. 5 to 6. 1 over a period of 34 days. It was demonstrated in the laboratory that bacteria possessing the enzyme urease were present in the cooling water. A number of biocides were screened for their ability to inhibit growth of ammonia